Extracorporeal membrane oxygenation (ECMO) is a technique that involves oxygenation of blood outside the body, and provides support to selected patients with severe respiratory or cardiac failure. The two major ECMO modalities are venoarterial and venovenous. Data from several randomised trials support the use of ECMO in neonatal respiratory failure, and a recent randomised controlled trial of ECMO in adults has produced encouraging results. The evidence base for ECMO use in cardiac disease is developing, but progress has been slowed by considerations of clinical equipoise and evolving indications for ECMO. Advancing ECMO technology and increasing experience with ECMO techniques have improved patient outcomes, reduced complications and expanded the potential applications of ECMO. Awareness of the indications and implications of ECMO among doctors managing patients with severe but potentially reversible respiratory or cardiac failure may help facilitate better communication between health care teams and improve patient recovery.